The present invention relates generally to yarn texturizing devices. More particularly, the present invention concerns an improved fluid jet bulking device and method in which a turbulent compressible fluid flow effects the bulking of a multi-filament yarn.
Fluid jet bulking of multi-filament yarns has long been known in the art. In one common method of fluid jet bulking, a compressible fluid passes coaxially into intimate association with an untextured yarn, and texturizes the yarn. The yarn and the fluid then exhaust from a common outlet. Typically, a yarn feed needle is provided which includes a longitudinally extending bore through which the multi-filament untextured yarn is supplied in an essentially continuous manner. The yarn feed needle is usually contained within a housing having an inlet connected with the supply of pressurized compressible fluid and having a discharge opening through which both the compressible fluid and the texturized yarn are exhausted. The compressible fluid commingles with the multi-filament yarn adjacent the exhaust opening and, by virtue of turbulence in the compressible fluid, the compressible fluid is effective to texturize and increase the bulk of the multi-filament yarn. See, for example, U.S. Pat. No. 2,982,082, issued on May 2, 1961.
Through the years, various attempts have been made to increase the efficiency of the fluid jet bulking resulting from apparatus as described above. For example, it has been proposed to alter the shape of a turbulence chamber immediately adjacent a discharge opening to thereby enhance the level of turbulence acting to texturize the yarn. See, for example, U.S. Pat. No. 3,863,309, issued Feb. 4, 1975.
In the known devices, turbulence is generated in the pressurized compressible fluid at a single location, that location being where the fluid jet commingles with the untexturized multi-filament yarn. Coincidentally, the velocity of the pressurized fluid at this location tends to be accelerating toward a discharge opening. This accelerating flow field transports turbulence of the fluid downstream at a relatively high rate to the discharge opening. Accordingly, turbulent eddies generated by the known phenomena tend to be transported away from the region of commingling with the yarn with which interaction is intended before the turbulent eddies have an adequate opportunity to fully develop for interaction.
With texturizing devices having turbulence generation at a single location, as disclosed in the prior art, the required mass flow rate of pressurized compressible fluid is unnecessarily high due to the poor efficiency of turbulence generation and the poor utilization of available turbulent energy. When dealing with apparatus used on a commercial scale, such inefficiencies lead to higher production costs and, therefore, more expensive finished products.
While efficient utilization of turbulent energy is one deficiency of the known fluid jet bulking devices, another problem concerns the characteristics of the texturized multi-filament yarn. More particularly, the yarns produced by previously known devices tend to have wild loops which protrude laterally from the texturized yarn. These wild loops, when the yarn is processed to make a textile fabric, exhibit a tendency to snag on adjacent objects causing pulls and the like which can detract from the aesthetic appeal of that fabric as well as from the suitability of using that fabric for certain applications.
In view of the foregoing, it is apparent that the need continues to exist for a fluid jet bulking device which overcomes problems of the type noted and which exhibits an improved turbulence generation and utilization efficiency while improving characteristics of the texturizing yarn.